Inside SpaceX’s Texas Rocket-Testing Facility

Shortly before 7 a.m. ET this morning, SpaceX engineers in Hawthorne, California, will be watching their monitors as the Dragon spacecraft makes its final approach to the International Space Station. As the on-board Draco thrusters make a final few bursts to maneuver towards the ISS, another team of SpaceX engineers in McGregor, Texas, will be watching to see if the small engines they tested extensively will perform as expected and steer the spacecraft within reach of the station's robotic arm.

Many of those same engineers are undoubtedly also busy reviewing data and images from Sunday's launch. About 79 seconds after lift-off, one of the nine Merlin rocket engines suffered a failure and had to be shut down during the ascent. That same engine had been fired on a test stand above the central Texas grasslands and performed perfectly before it was even considered to be counted on for Sunday's launch. But as SpaceX is fond of reminding us, this is rocket science and things don't always go as planned

While SpaceX builds all of its own rocket engines and thrusters at its Hawthorne headquarters, before they can fly, they must pass through McGregor where the company tests each new engine off of the assembly line, as well as those being developed for future missions to orbit and beyond.

McGregor is like many small towns in Texas. It is located just south of the once anonymous town of Crawford and McGregor High School's football stadium features a fair amount of seating for a town of less than 5,000.

But there is one thing McGregor residents experience that is unlike any other Texas town. Every so often its inhabitants hear and feel the rumble of rocket engines as the air around them pulses courtesy of one of the biggest employers in town. And SpaceX is expanding.

"We're building more test stands because we're ramping up production, because we have this big manifest in front of us," says SpaceX spokeswoman Kirstin Grantham.

The seven test stands are in constant operation. The facility in McGregor currently operates 18 hours a day, six days a week. Engines are fired, stages are pushed and pulled, and Dragon capsules are taken apart and inspected. The company's headquarters and factory in sunny southern California gets a lot of the attention, but most of the noisy, dirty and critical testing work is done just outside this small central Texas town nestled in amid the farm fields.

Above is the biggest, loudest test performed in McGregor. All nine Merlin engines are tested as a complete first-stage unit just as they will be used during launch. And everybody in town knows when the testing takes place.

UPDATE - At 9:03 a.m. ET the Dragon spacecraft was successfully attached to the International Space Station.

Photo: SpaceX

Before the first stage is tested as a unit, each Merlin engine goes through its own battery of exams. Here, the main test stands for the Merlin engines can be seen in between trial runs. The blue stand in the middle is used for testing the Merlin engine employed during the second stage of the ascent. On the left is a double test stand where one engine can be tested while another is being prepared for firing.

The large white tanks hold the water used for sound suppression and cooling.

Photo: Jason Paur/Wired

Another view of the second stage test stand, also known as the "M-Vac" stand, before the blue surrounding structure was added. Here a second stage engine is being tested. The second stage of the rocket uses a single Merlin engine to boost the Dragon once the first stage has delivered into space, which is why the engine is tested first in a vacuum environment.

Photo: SpaceX

The "flame bucket" can be found at the bottom of each test stand. The steel pipe structure floods the area with water during test firings to suppress the noise and to serve as a coolant. A similar device is used on the launch pad in Cape Canaveral.

Photo: Jason Paur/Wired

The Falcon 9 that launched on Sunday uses Merlin 1C engines that produce 125,000 pounds of thrust – apiece – at sea level. A new Merlin 1D engine can be seen during a test firing. The 1D will generate 147,000 pounds of thrust at sea level and will have the highest thrust-to-weight ratio of any rocket engine ever used.

The Merlin 1D is scheduled to be used on Falcon 9 launches in 2013 and beyond in geosynchronous transfer orbits.

Photo: SpaceX

In addition to testing the larger Merlin engines that power the first and second stage of the Falcon 9, the smaller Draco thrusters are also tested in McGregor.

The Dragon spacecraft comes equipped with 18 Draco thrusters that are used for maneuvering during orbit and re-entry. Each of the Dracos (and soon the upgraded Super Dracos), are tested individually in a "space vacuum" chamber. The thrusters are tested in very short pulses, similar to how they are used during flights.

Because so little propellant is necessary for these extremely short pulses, during the testing three lasers are used to measure the change in propellant. The lasers can be seen near the top of the flat metal panel, above the black insulation. The propellant is known as a hypergolic propellant, meaning the mixture of monomethyl hydrozene and nitrogen tetroxide (one on each side of the vacuum chamber) spontaneously combust when they come in contact with each other.

As the propellants pass through a finger-sized glass tube on the test stand, the lasers measure the level of the meniscus with sub-millimeter precision.

Photo: Jason Paur/Wired

Inside the space vacuum chamber a Draco thruster glows during a test firing.

Photo: SpaceX

In addition to testing in the space vacuum chamber, Dracos are also developed on a nearby outdoor test stand. Engineers can use the software that will control the Dragon to test-fire the thrusters and analyze the pulse firings to better tune the maneuvers that will take place in orbit.

During maneuvers, the thrusters are often pulsed for fractions of a second. During the last flight to the ISS, the thrusters could be seen pulsing as the Dragon maneuvered away from the station. SpaceX says it's similar to a shotgun blast each time the thruster is fired, both in the amount of fuel used and the thrust produced. Here a quad of Draco thrusters can be seen during test firings on the stand in McGregor.

Photo: SpaceX

During re-entry – and potentially during a future manned launch aborts – the Dracos will be used for longer periods than normal during orbital maneuvering, often many seconds at a time.

In the photo above, a Super Draco is tested on the outdoor stand during a long-duration firing. The "shock diamond" pattern in the exhaust plume is created due to the pressure difference between the exhaust and outside air. The same thrusters that will be used for orbital maneuvering in short pulses will also provide the thrust for several seconds to almost instantaneously push the Dragon capsule clear and away from the Falcon 9 rocket if a launch was to be aborted during lift-off or on ascent.

Photo: SpaceX

There are still signs of the Cold War climate in McGregor left over from when the facility was built for the Navy in 1960. Some offices, along with control rooms where a myriad of screens allow engineers to carefully monitor each and every engine and structure test, are housed in a partially buried bunker. The structure could stand in as a movie set in some post-apocalyptic thriller. It even has a vault door several feet thick.

The "block house" was the only habitable building when SpaceX took over the facility in 2003. And it had the only bathroom. So in those early days it housed not only offices and control rooms, but also the fabrication shop, machine shop and any other job that needed to protect occupants from the heat.

Photo: Jason Paur/Wired

After the Navy built the block house in 1960 it was filled with room-sized computers and tape drives connected to copper wires that transmitted a few hundred channels of data from a single test stand. Much of the early ICBM testing was done here as well as the first stage of the Minuteman missile.

Photo: Jason Paur/Wired

Today the building has been upgraded and redecorated. Each of the six control rooms can handle both Merlin and Draco thruster testing.

Young engineers in T-shirts and jeans watch three computer screens each as well as a main display at the front of the room as thousands of channels of data are fed through fiber-optic cables from seven test stands running 18 hours a day and six days a week. And with a massive backlog of launches on the books, SpaceX's testing facility is only going to get busier.

On the day we visited, one of the new Super Draco thrusters was being tested. The firing lasted just two seconds, and the team averages at least one engine test per day. The pace will pick up in the coming months.

Photo: Jason Paur/Wired

When you work at a rocket testing facility, it's easy to recycle some of the equipment to make unique furniture for the offices.

Around 160 people work at SpaceX's McGregor test facility and near these cubicles photos from engine testing decorate the "Hall of Flame."

Photo: Jason Paur/Wired

In addition to testing engines in McGregor, SpaceX also puts other parts of the Falcon 9 and Dragon through their paces. The structures are pushed, pulled and shaken.

In this photo, the Dragon spacecraft is tested on one of the structural testing stands.

The Dragon capsules return to McGregor after each flight for post mission analysis. The Dragon used on the first mission to the ISS sits in the simply named 'Dragon Building' after its historic flight in May. The building is a nondescript steel structure that could be mistaken for something a rancher would keep his farm equipment.

The SpaceX technicians and engineers carefully inspect the capsule, taking much of it apart to analyze how everything worked during the flight. During our visit, the outer panels on the lower third of the spacecraft were removed and the team was inspecting the Draco thrusters and associated systems including the foil wrapped propellant tanks which are slightly larger than basketballs. We weren't able to take pictures of the outside of partially disassembled Dragon, but above is how it looked when it arrived after its mission to the ISS.

The heat shield shows asymmetric burn marks from re-entry, with one side receiving less of the heat and showing less discoloration. This side is seen above and is the area that contains the avionics and cargo door, and is more protected from the 3,000 to 4,000 degrees Fahrenheit experienced during re-entry. The heat shield material is a very low-density ceramic that's easy to mar with the push of a fingernail.

Photo: SpaceX

The inside of the Dragon capsules are also inspected and dissected.

Here a technician works on removing one of three avionics boxes that houses the antennas and voice communications. At this point, only the cargo had been removed from the Dragon that went to the ISS.

Inside the Dragon, more of SpaceX's "eye on the future" could be seen. Though not visible on the outside (or in this picture), the Dragon does have windows installed for future manned missions. Despite looking rather cramped, the Dragon will be able to seat seven, and an entire Russian Soyuz capsule could fit inside.

Photo: Jason Paur/Wired

This rather unassuming building is where Falcon 9 rockets are assembled after the components are tested.

The plain structure houses the rocket, and during our visit the fifth Falcon 9 was sitting inside ready to be disassembled again before being shipped to Cape Canaveral where it will be used for the second commercial resupply mission sometime later this year or in early 2013.

Inside you have to carefully navigate a mishmash of cooling and ventilation hoses that cover the floor next to the Falcon 9 rocket.

Giving the rocket a good knock, it's surprising how thin and lightweight the structure sounds – more like a thin barrel than something designed to endure space flight. Unfortunately, we weren't able to take any photos inside the building.

Outside the hangar is part of an interstage sitting on a trailer. The insterstage connects the first and second stage (and covers the second stage Merlin engine).

Photo: Jason Paur/Wired

The largest testing stand is the tripod that is used for testing the first stage with all nine Merlin engines (seen in the opening image). Situated right next to the road, the large test stand also serves as a psuedo-billboard for the McGregor facility.